MOLECULAR-CLONING AND FUNCTIONAL EXPRESSION OF THE GENE ENCODING THE HUMAN PROTEINASE-ACTIVATED RECEPTOR-2

We previously reported the molecular cloning of a mouse guanosine-nucl eotide-binding-protein-coupled receptor similar to the thrombin recept or. Since the physiological agonist was unknown, the receptor was name d proteinase-activated receptor 2. We describe here the cloning and fu nctional expression of the gene encoding the corresponding human recep tor. The gene is divided into two exons separated by about 14 kb intro nic DNA. The deduced protein sequence is 397 amino acids long and 83% identical to the mouse receptor sequence. Within the extracellular ami no terminus, the residues predicted to form the tethered agonist ligan d differ between the two receptors; of the first six residues only fou r are conserved. At positions five and six, a lysine residue and a val ine residue, respectively, have replaced arginine and leucine residues found in the mouse sequence. When the human receptor is expressed in Chinese hamster ovary cells, it can be activated by low nanomolar conc entrations of the serine proteinase trypsin acid by peptides made from the receptor sequence. Northern-blot analysis of receptor expression showed that the receptor transcript is widely expressed in human tissu es with especially high levels in pancreas, liver, kidney, small intes tine and colon. Moderate expression was detected in many organs but no ne in brain or skeletal muscle. By fluorescence in situ hybridization, the human proteinase-activated receptor 2 gene was mapped to chromoso mal region 5q13, where, previously, the related thrombin receptor gene has been located.